Boiling Phenomena and Effects of Water Temperature on Heat Transfer in the Process of Immersion Cooling of a Heated Steel Plate

Abstract

In order to apply an immersion cooling to the manufacturing process of iron and steel, it is necessary to clarify the characteristics of the immersion method. As the first step, the boiling phenomena and cooling abilities were investigated for a steel plate of about 930°C immersed into the still water of 20-90°C. The results obtained are as follows:
(1) When a plate is immersed, nucleate boiling begins from the edge of a plate and subsequently travels to the center.
(2) When a plate is horizontally immersed, the lower surface of the plate is covered with stable vapor film. Consequently, the released heat from the lower surface is smaller than the upper.
(3) When a 28×220×220mm³ plate is vertically immersed, the heat transfer coefficient α between the plate and water is a function of surface temperature θ_s and water temperature θ_w. These are related by the following equation. Here, A, B, and K are constants which depend onθ_s.
α= [10 (A+B·θ_s)] · [1-K· (θ_w-26)]
[α]: kcal/mm²·h·deg, [θ_s, θ_w]: °C
(4) α reaches a maximum in the θ_s range from 200 to 300°C and its value is 7-10×10³kcal/mm²·h·deg in the θ_w range from 20 to 30°C.